Stacy potts



(No Model.)

S. POTTS.

. SCREW. No. 297,004. Patented Apr. 15, 1884.

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N. PETERS. Pluto-lithograph. Wulinm DC.

UNITED STATES ATENT OFFICE.

STACY POTTS, OF WASHINGTON, DISTRICT OF COLUMBIA.

SCREW.

SPECIFICATION forming part of Letters Patent No. 297,004, dated April 15, 1884.

Application filed October 18, 1883.

To all whom it may concern;

Be it known that I, STACY POTTS, a citizen of the United States, residing at Washington, in the District of Columbia, have invented certain new and useful Improvements in Screws; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

Heretofore screws have been provided with slots or grooves of the same depth from end to end. The disadvantage of this form is that the screw-driver is apt to slip from the slot or groove, causing the walls thereof to break or become so worn that ascrew-driver can-obtain no hold. To overcome this defect the bottom of the groove or slothas been provided with elevations or corrugations which require a special form of screw-driver, as said elevations or corrugations reduce the depth of the slot and groove to such an extent that the usual form of screwdriver can obtain no hold.

The object of my invention is to provide a screw which can be used either with the ordinary form of screw-driver or with one specially designed for the purpose.

To that end the nature of my invention consists of constructions and combinations,which will hereinafter be described and claimed, reference being had to the accompanying drawings, in which Figure 1 represents an elevation of part of a screw-driver having a rounded bit, and a screw having the upper part in section on the line of the groove or slot; and Fig. 2, asimilar view, showing another form of depression below the groove, and a screw-driver adapted to be used on that form.

A represents the screw, and B the screwdriver. Thescrew is provided with the usual slot or groove, a, extending across the head.

(No model.)

This groove is provided with a depression, a, formed near the center, and may be of any desired form. In Fig. l the depression a is of semicircular form, the lowermost part being on the median vertical line of the screw. In Fig. 2 the depression is wedgeshaped, the apex being on the same line as the form shown in Fig. 1. i

It is obvious that this form of screw will permit of the use of the ordinary screwdriver, while at the sametime being adapted to special forms. If, as is often the case, one or both sides of the head should break away, the depression will afford sufiicient holdfor a screwdriver of special form, or to the many tools found in a workmans kit.

It will also be seen that when a special form of screwrdriver is used the screw will afford a better hold than those provided with the ordinary slot or groove, and that there is less liability of the screw-head breaking when an unusual strain is caused by the resistance of the material in which the screw is being forced.

I am aware that screw-heads have been provided with an angular cavity in place of the usual slot or nick, and that I do not claim, as my device differs from them, in that itis provided'with the usual nick or slot, and a depression the bottom of which extends from end to end of said nick or slot. Therefore what I claim is A screw the head of which is provided with a dri ve-slot extending entirely across and sloping downward toward the center from the 0pposite ends, substantially as illustrated and described.

In testimony whereof I affix my signature in presence of two witnesses.

STACY POTTS. Witnesses:

M. F. HALLEOK, T. F. HOLDEN. 

